Method and apparatus for drying wavily running strip with hot blasts

ABSTRACT

An arrangement for drying a strip of stock comprising the steps of running a long, thin, continuous strip of stock having a liquid coating thereon through a drying zone between overlaping convex blowing faces which cause said strip to travel along in a regular wavy running pattern by blowing film of hot air onto either side of said stock which consequently is dried while running in a practically tension-free, extensible and shrinkable state.

[ 51 June 13, 1972 United States Patent Kobayashi [54] METHOD ANDAPPARATUS FOR 3,216,638 11/1965 Brickle etDaniels................................34/l56 X WITH HOT BLASTS PrimaryExaminer-Carroll B. Dority, J r. Anomey-George B. Oujevolk [72]Inventor: Tadashi Kobayshi, 1560-2 Higashihara lenma, Fuji, Japan Aug.20, 1970 An arrangement for drying a strip of stock comprising the [22]Filed:

[2 l Appl. No.: 65,539 steps of running a long, thin, continuous stripof stock having a liquid coating thereon through a drying zone betweenoverlaping convex blowing faces which cause said strip to travel along.34/156 [52] US. C

in a regular wavy running pattern by blowing film of hot air 7 7 l/ 6 22 no 5 1 m4 2 m3 "2 I 4 3 mi o C m .mF .ll. 118 55 [.1

onto either side of said stock which consequently is dried while runningin a practically tension-free, extensible and shrinkable state.

2Clains,3DnwingFlgures References Cited UNITEDSTATESPATENTS PATENTEDJUM13 I972 SHEEI 1 BF 3 FIG./

INVENTOR T mmm K013 AvAsH l QIEORGE E Q via/c LR ATTORNEY PATEHIEQJUH 13 I872 3, 668, 788

- sum 30F 3 Tm mm KQBM W I INVENTOR BY QKLLLRGLJL Q m L x ATTORNEYMETHOD AND APPARATUS FOR DRYING WAVILY RUNNING STRIP WITH HOT BLASTSBACKGROUND OF THE INVENTION shrinkable state when the stock is coatedwith a chemical solution, a plastic, or another coating.

BRIEF DESCRIPTION OF THE PRIOR ART It has been a matter of greatinterest in industry how to dry a long, thin, continuously running stripof paper, plastic film, metal foil, orother base stock in a practicallytension-free, extensible and shrinkable state when the material iscoated with a chemical solution, a plastic, a pigment, an ink, or othercoating. In recent years more and more new base stock and coatings havebeen developed, giving birth to anever-growing variety of new products.In addition, strips of such stock to be dired are becoming broader andbroader. All this makes it increasingly difficult for the conventionaltype of drier to dry such products without unfavorably affecting theirultimate properties or to do so at higher speeds.

Specifically, the conventional drier of the belt-conveyor type mustapply considerable pressure to the strip of stock in the lengthwisedirection to keep it running properly, and this prevents the stock fromexpanding or shrinking freely, with the result that it tends to bewrinkled or curled, or lose some of its essential properties.

If the conveyor speed of the conventional drier is to be adapted to eachspecific type of stock to be dired so that the stock can expand orshrink freely as it is dried continuously fro'minitial evaporation ofmoisture to complete drying, it is necessary to use a different drivefor each type of stock, plus a device for automatically efiecting fineadjustments of the tension of the stock. To allow the stock to shrinkfreely in width, moreover, it is necessary to minimize contact betweenthe stock and the conveyor belt. With the conventional type of drier,these things are hard to do, and are not being done in practice.

In addition, because the conventional drier is a conveyor type, itrequires a very elongated floor space for installation, and the factoryspace above and below the drier normally must remain empty and useless.From the viewpoint of space utilization, the conventional drier is veryuneconomical. Although many attempts have been made to provide aneconomical drier for such stock, none, as far as I am aware has everbeen successful when carried out into practice on a commercial scale.

OBJECTS OF THE INVENTION It is an object of the present invention toprovide a method and apparatus for drying a long, thin, continuouslyrunning strip of paper, plastic film, metal foil, or other base stockcoated with a chemical solution, plastic, pigment, or other coatingwithout unfavorably afiecting their properties.

Another object of the present invention is to provide a method andapparatus for drying such a strip of stock as described above withoutmechanically marring the surface of either side thereof.

The invention also contemplates providing a method and apparatus fordrying such a strip of stock as described previously without causing itto become wrinkled, curled, or otherwise physically changed.

It is also an important object of the invention to provide a morecompact apparatus for drying such a strip of stock as described thanthose conventionally used therefore, and more particularly, to providesuch an apparatus which requires less elongated floor space forinstallation.

SUMMARY-OF THE INVENTION Specifically, the present invention proposes touse a film of jetted hot air to keep astrip of stock to be dried runningvertically in a wavy pattern while being subject to no tension inthewidthwise direction and to very little tension in the lengthwisedirection, thus allowing said strip to be dried in a manner suited toits physical properties. Running in a wavy course, moreover, said stripis relieved of internal strains through flexing, and therefore finishedfree of curling, waving, and such other unfavorable unilateral habits.Moreover, an apparatus according to the present invention has muchimproved thermal efficiency and drying capacity since hot air is blownonto said running strip at a very close range.

In addition, such an apparatus can be about a third or less in size of acomparable drier of the conventional type, and does 'not require such anextremelyelongated floor space for installation as the latter does, withthe result that no idle space oc- I curs above or below the apparatus.Better-utilization of plant space is thus made possible.

Other objects and advantages of the invention will become apparent fromthe following description of an apparatus representing a preferredembodiment thereof taken in conjunction with the accompanying drawingsin which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows jet boxes and a jetcylinder in'elevation as well as their arrangement in said apparatus;

FIG. 2 shows said apparatus in ageneral frontal elevation; and,

FIG. 3 shows schematically the inside of the apparatus of FIG. 2 insection taken on line 3-3.

DETAILED DESCRIPTION In the drawings, numeral I refers to any one of anumber of jet boxes, each having a convex face 2 with jet perforations3, which are closely distributed in the middle and less so toward theperiphery.

XX represents the base line of a wave pattern, and runs roughlyvertically. A number of such jet boxes as described above are arrangedin a vertical row on either side of line X- X, each box having thegreater part of its convex face 2 protruding across said base line andoverlaping the convex face 2 of each adjacent jet box on the other sideof line XX with a slight clearance between said faces. 7

The embodiment of the invention illustrated in FIGS. 2 and 3 has adrying section A1 consisting of four jet boxes arranged in two mutuallyconfronting and staggered vertical rows as described above, a similardrying section A2 installed back to back with Al, said two dryingsections thus forming group A, and a similar group B made up of dryingsections B1 and B2 which are identical with A1 and A2, respectively. Inaddition, below and between drying sections A1 and A2, there is a jetcylinder 4 with perforations 5 on its side; and a similar jet cylinder 6is provided below and between drying sections B1 and 82. Above andbetween drying sections A2 and BI, a drying roll 7 provides a means ofconnection between groups A and B. These groups A and B, together with afeed roll 8 which introduces a strip of stock P to be dried into groupA, and a discharge roll 9 which leads the dried stock P out of group Bare enclosed in a hood 10. Inside the hood 10, a hot air chamber 11 ispartitioned off. Hot air supply ducts l2 and 13 lead from this chamber Il to said jet boxes I and jet cylinders 4 and 6. j

Heaters 14a and 14b, and exhaust ducts 15a and 15b are also providedinside said hood 10 above jet box groups A and B. Ducts l6 collect hotair from the middle between the heaters 14a and 14b and lead it to fans17, which send said hot air to supply ducts 18. Also, said exhaust ducts15a and 15b lead to a fan 19, which discharges air outside, while freshair is introduced through inlets 20.

3 OPERATION OF THE INVENTION How the present invention works isnowexplained with reference to this particular embodiment thereof. Astrip of work P to be dried is introduced via the feed roll 8 into thehood 10, and runs down along the convex faces 2 of the jet boxes 1 ofdrying section Al, around the jet cylinder 4, up along the convex faces2 of the jet boxes 1 of drying section A2, around the drying roll 7,down along the convex faces 2 of the jet boxes 1 of drying section Bl,around the jet cylinder 6, up along the convex faces 2 of the jet boxes1 of drying section B2, and finally out of the hood via the dischargeroll 9. Said strip P is run through this route by a take-up drive at thedischarge end of said drying apparatus.

8 Air inside the'hood 10 is heated by the heaters 14a and 14b, and ledvia the ducts 16 to the fans 17, which sends it in hot blasts throughthe supply ducts 18 into the hot air chamber 1 1. From this chamber thehot air enters the jet boxes 1 and the jet cylinders 4 and 6, from whichit is blown through perforations 3 and 5.

Since jet box groups A and B are identical in operation, the followingexplanation is given with reference to group A. A strip of stock Prunning between the partly opposing convex faces 2 of the jet boxes ofeach drying section is kept off each of said convex faces by hot airjetted from the perforations 3 therein. Carried on a thin film of air inthis manner, said stock P follows a wavy route through said dryingsection. Since the stock thus running is subject to no tension at all inthe widthwise direction, and can expand or shrink freely in saiddirection it is finished, free of wrinkling waviness. In the lengthwisedirection, the stock meets with no frictional resistance from the jetboxes 1, and is kept running under only slight tension. Consequently,mechanical action hardly affects the essential properties of said stock,and when dry it shows little tendency to curling since it has beenflexed repeatedly back and forth during drying.

For another thing, the surfaces of said stock P are not marredmechanically while running through said drying sections since the stockis carried on a film of hot air from each jet box.

Furthermore, since several such groups of dryingsections as describedpreviously may be installed vertically one upon another, a dryingapparatus according to the present invention may be made compact, anddoes not require an elongated floor space for installation as acomparable drier of the conventional type does, while being better thanthe latter in thermal efficiency and drying capacity.

Considering the nature of the invention, it is not limited, of course,to the particular embodiment described above, which involves two groupsof jet boxes A and B.

Although the present invention has been described in conjunction with apreferred embodiment, it is to be understood that modifications andvariations may be restored to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and appended claims.

I claim: v

1. In an apparatus for drying a strip of stock having a wet coatingthereon comprising: a rectangular frame for defining an elongatedvertical path of travel for said strip of stock therein; first andsecond vertical rows of a plurality of boxes supported by said frame andarranged one over the other, said boxes having convex vertical faces,the boxes in one vertical row being offset with respect to the boxes inthe adjoining vertical row, the convex faces in one row being nestedwith respect to the convex faces in said adjoining row so as to define awavy path of travel therebetween, each face having a plurality of hotgas outlet apertures thereon; hot gas supply ducts connected to saidboxes with means to supply hot gas to said ducts; and, an input andoutput section in said frame with stock strip feed and discharge rollsin said section to feed said stock strip nto and out of said wavy pathof travel; the improvement therein wherein said first and secondvertical rows of boxes form a first group, at least one second groupalongside said first group, and, at least one cylinder between saidfirst and second group at one end thereof, the circumference of saidcylinder nesting between corresponding convex faces in both said firstand second groups, with a plurality of hot gas apertures in saidcylinder. 1

2. An apparatus as claimed in claim I, there being a plurality ofparallel vertical groups with cylinders between each of said groups atthe top and bottom ends thereof, so as to define an extended travel pathfor said stock strip.

1. In an apparatus for drying a strip of stock having a wet coatingthereon comprising: a rectangular frame for defining an elongatedvertical path of travel for said strip of stock therein; first andsecond vertical rows of a plurality of boxes supported by said frame andarranged one over the other, said boxes having convex vertical faces,the boxes in one vertical row being offSet with respect to the boxes inthe adjoining vertical row, the convex faces in one row being nestedwith respect to the convex faces in said adjoining row so as to define awavy path of travel therebetween, each face having a plurality of hotgas outlet apertures thereon; hot gas supply ducts connected to saidboxes with means to supply hot gas to said ducts; and, an input andoutput section in said frame with stock strip feed and discharge rollsin said section to feed said stock strip into and out of said wavy pathof travel; the improvement therein wherein said first and secondvertical rows of boxes form a first group, at least one second groupalongside said first group, and, at least one cylinder between saidfirst and second group at one end thereof, the circumference of saidcylinder nesting between corresponding convex faces in both said firstand second groups, with a plurality of hot gas apertures in saidcylinder.
 2. An apparatus as claimed in claim 1, there being a pluralityof parallel vertical groups with cylinders between each of said groupsat the top and bottom ends thereof, so as to define an extended travelpath for said stock strip.